Oscillopsia in patients who have brain stem disorders but not nystagmus is attributed to a failure of the vestibular-ocular reflex (VOR) to compensate for head movements. We report a patient who had marked head titubation and oscillopsia in aggressive multiple sclerosis but no nystagmus. Her severe head titubation precluded our ability to measure a VOR accurately. Because oscillopsia has also been described after rapid voluntary head oscillations in normal subjects, we queried whether the oscillopsia in our patient could be ascribed to the head movement alone. Six normal control subjects did not experience oscillopsia while shaking their heads at the same frequency as the patient's titubation. We conclude that the oscillopsia in our patient was probably the result of an impaired VOR or an alternative compensatory mechanism.